#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<assert.h>
char* My_strcat(char* arr1, const char* arr2)
{
	char* start = arr1;
	assert(arr1 && arr2);
	while (*start)
	{
		start++;
	}
	while (*start++ = *arr2++)
	{
		;
	}
	return arr1;
}
int main()
{
	char arr1[30] = "hello ";
	char arr2[10] = "world";
	My_strcat(arr1, arr2);
	printf("%s\n", arr1);
	return 0;
}